This invention relates in general to transducers and in particular to a new and useful transducer of the electrodynamic type having a diaphragm with conducting tracks disposed within a flat magnetic system permeable to sound.
Such electroacoustic transducers are currently used only in head sets, because the surface-driven diaphragm does not tend to partial oscillations and makes possible an undistorted, largely linear, reproduction. Due to the reversibility of the electrodynamic principle, their use as sound receivers is sometimes referred to in the technical literature dealing with transducers of this kind without specifying the construction or acoustic operating characteristics of such a microphone, not to speak of its design as directional sound receiver. It is evident, in view of the improved miniaturization of active and passive electronic component parts, that capacitive transducers, particularly those with an electret diaphragm, are superior to electrodynamic microphones, wherever highest requirements are imposed on quality. An allowance is made for accommodating, in the casing of a capacitive transducer, an amplifier or impedance transformer supplied with current from a battery, also incorporated in the casing or through the microphone cable. Either of those manners of supply may cause disturbances. For example, with a failure of the battery due to an oversight, such as failing to timely switch off the battery, no exchange may be available. With a supply through the microphone cable, not only is an amplifier with a corresponding connection needed but interruptions may also occur in the high-duty microphone cable, preventing the use of the microphone.